Would You Ever Take a Vacation Alone?

Right now, my guy friend Kenan (of blind-date fame) is on a two-week vacation by himself in South America. He's thrilled to be hiking alone in the desert and then hanging out (and rocking out) in Buenos Aires. But I was thinking...

...I would be freaked out to do that on my own, especially hiking in the desert. (Eeps!) But maybe it would be fun and invigorating to travel to a busier place alone, like Tokyo or Paris or...Reykjavik, Iceland!

What about you guys? Would you ever take a vacation alone? Have you? Where would you go? Or would you prefer to always travel with a partner?